1. Technical Field
The present invention relates to a projector.
2. Related Art
As a light source for a projector, a laser light source which is capable of obtaining high output light has gained attention. The laser light source has advantages such as superior color reproducibility, easier instant lighting and longer lifespan compared with a high pressure mercury lamp. However, since laser light is coherent light, speckles which occur due to interference are displayed on a screen, which causes the display quality to be lowered.
Technologies for solving this problem have been studied. For example, in a projector disclosed in JP-A-2010-197916, characteristics and arrangement of a light modulation device are set so that a light distribution angle with regard to one arbitrary point on a screen is equal to or larger than a predetermined angle. It is known that if the light distribution angle becomes large, it is possible to suppress lowering of the display quality due to speckles (speckle noise).
However, it is difficult to sufficiently suppress speckle noise only by setting a large light distribution angle.
For example, a fly-eye optical system or a rod optical system may be installed on an optical path of light between a diffusion device and a light modulation device so as to uniformize intensity distribution of light emitted from the diffusion device. Diffusion intensity distribution of the light emitted from such an optical system becomes discrete, and such angular distribution is maintained even after passing through the light modulation device. Thus, angular distribution of the light incident on a screen becomes noticeably ununiform, and a projection image may be deteriorated due to speckles.